Sounds like you have a corrupted user profile.
When you log in (or try to) do you get the message "you have been logged in with a temporary user profile" or something similar?
If so, once logged in, go to Control Panel, User Accounts and create a new user.
Log off the current temporary one, log into your new one.
Go to Windows Explorer and you can now copy your old user Docs, Pics, Music etc from the old user to the new one.
That is, from C:\users\old name\ to C:\users\new name\